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Journal ArticleDOI

Stress, reproduction, and adrenocortical modulation in amphibians and reptiles.

01 Jan 2003-Hormones and Behavior (Academic Press)-Vol. 43, Iss: 1, pp 39-47
TL;DR: It is suggested that several ecologically based ideas, such as variability in the length of the breeding season and lifetime reproductive opportunities, can be used to explain the utility of adrenocortical modulation in amphibian and reptilian species.
About: This article is published in Hormones and Behavior.The article was published on 2003-01-01. It has received 504 citations till now.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the authors review many of the potential stressors that may adversely affect animals living in captivity and present a suite of behavioral or physiological responses that will clearly indicate the cause of those responses; rather, it is up to us as managers and caretakers of animals in captivity to evaluate enclosures and husbandry practices to ensure the optimal well-being of animals.

839 citations


Cites background from "Stress, reproduction, and adrenocor..."

  • ...that are particularly undesirable for animals maintained in captivity, including increased abnormal behavior (Capitanio, 1986), increased self-injurious behavior (Bellanca and Crockett, 2002; Reinhardt and Rossell, 2001), impaired reproduction (Moore and Jessop, 2003; Tilbrook et al., 2002) and immunosuppression (Kanitz et al....

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  • ...…animals maintained in captivity, including increased abnormal behavior (Capitanio, 1986), increased self-injurious behavior (Bellanca and Crockett, 2002; Reinhardt and Rossell, 2001), impaired reproduction (Moore and Jessop, 2003; Tilbrook et al., 2002) and immunosuppression (Kanitz et al., 2004)....

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Journal ArticleDOI
TL;DR: It is argued that biological actions of GCs at "non-stress" seasonal concentrations play a critical role in the adjustment of responses that accompany predictable variability in the environment and demand more careful consideration in future studies.

755 citations

Journal ArticleDOI
TL;DR: Overall, baseline cort can predict the relative fitness of individuals and populations, but the relationship is not always consistent or present.
Abstract: Baseline glucocorticoid (cort) levels are increasingly employed as physiological indices of the relative condition or health of individuals and populations. Often, high cort levels are assumed to indicate an individual or population in poor condition and with low relative fitness (the Cort–Fitness Hypothesis). We review empirical support for this assumption, and find that variation in levels of baseline cort is positively, negatively, or non-significantly related to estimates of fitness. These relationships between levels of baseline cort and fitness can vary within populations and can even shift within individuals at different times in their life history. Overall, baseline cort can predict the relative fitness of individuals and populations, but the relationship is not always consistent or present.

741 citations


Cites background from "Stress, reproduction, and adrenocor..."

  • ...Thus the demands of reproduction mightbeperceivedasanenvironmentalchallengebymany organisms [ 60 ], resulting in increased secretion of cort, reallocation of resources to reproduction, and a positive relationship between baseline cort and fitness....

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Journal ArticleDOI
TL;DR: Numerical projections show that an "evolutionary trap" toward extinction threatens populations in which there is a substantial mating cost for females, and environmental changes or management practices skew the ASR toward males.
Abstract: The adult sex ratio (ASR) is a key parameter of the demography of human and other animal populations, yet the causes of variation in ASR, how individuals respond to this variation, and how their response feeds back into population dynamics remain poorly understood. A prevalent hypothesis is that ASR is regulated by intrasexual competition, which would cause more mortality or emigration in the sex of increasing frequency. Our experimental manipulation of populations of the common lizard (Lacerta vivipara) shows the opposite effect. Male mortality and emigration are not higher under male-biased ASR. Rather, an excess of adult males begets aggression toward adult females, whose survival and fecundity drop, along with their emigration rate. The ensuing prediction that adult male skew should be amplified and total population size should decline is supported by long-term data. Numerical projections show that this amplifying effect causes a major risk of population extinction. In general, such an "evolutionary trap" toward extinction threatens populations in which there is a substantial mating cost for females, and environmental changes or management practices skew the ASR toward males.

367 citations

Journal ArticleDOI
TL;DR: There is probably not a single cause for global amphibian declines and the role of pathogens in inducing diseases that cause death is profoundly affected by four other ultimate factors: atmospheric change, environmental pollutants, habitat modification and invasive species.
Abstract: Greater than 70% of the world's amphibian species are in decline. We propose that there is probably not a single cause for global amphibian declines and present a three-tiered hierarchical approach that addresses interactions among and between ultimate and proximate factors that contribute to amphibian declines. There are two immediate (proximate) causes of amphibian declines: death and decreased recruitment (reproductive failure). Although much attention has focused on death, few studies have addressed factors that contribute to declines as a result of failed recruitment. Further, a great deal of attention has focused on the role of pathogens in inducing diseases that cause death, but we suggest that pathogen success is profoundly affected by four other ultimate factors: atmospheric change, environmental pollutants, habitat modification and invasive species. Environmental pollutants arise as likely important factors in amphibian declines because they have realized potential to affect recruitment. Further, many studies have documented immunosuppressive effects of pesticides, suggesting a role for environmental contaminants in increased pathogen virulence and disease rates. Increased attention to recruitment and ultimate factors that interact with pathogens is important in addressing this global crisis.

361 citations


Cites background from "Stress, reproduction, and adrenocor..."

  • ...Though moderate levels of corticosterone may promote reproduction by mobilizing energy stores (Moore and Jessop, 2003), chronically elevated corticosterone (and stress in general) inhibits reproductive development, behavior and fertility (Moore, 1983)....

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References
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Journal ArticleDOI
TL;DR: This model indicates that there may be widely different hormonal responses to male-male and male-female interactions and presumably equally plastic neural mechanisms for the transduction of these signals into endocrine secretions.
Abstract: A combination of field and laboratory investigations has revealed that the temporal patterns of testosterone (T) levels in blood can vary markedly among populations and individuals, and even within individuals from one year to the next. Although T is known to regulate reproductive behavior (both sexual and aggressive) and thus could be expected to correlate with mating systems, it is clear that the absolute levels of T in blood are not always indicative of reproductive state. Rather, the pattern and amplitude of change in T levels are far more useful in making predictions about the hormonal basis of mating systems and breeding strategies. In these contexts we present a model that compares the amplitude of change in T level with the degree of parental care shown by individual males. On the basis of data collected from male birds breeding in natural or captive conditions, polygynous males appear less responsive to social environmental cues than are monogamous males. This model indicates that there may be wi...

2,098 citations


"Stress, reproduction, and adrenocor..." refers background in this paper

  • ...Emerson (2001) has proposed an extension of the Challenge Hypothesis (Wingfield et al., 1990), termed the Energetics-Hormone Vocalization (EHV) Model, to explain the reported relationships between calling behavior and testosterone and corticosterone levels in male anuran amphibians....

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Journal ArticleDOI
TL;DR: Field work reveals that changes in responsiveness to LPFs have ecological bases, such as reproductive state, body condition etc., that in turn indicate different hormonal control mechanisms in the HPA cascade.
Abstract: SYNOPSIS. Superimposed upon seasonal changes in morphology, physiology and behavior, are facultative responses to unpredictable events known as labile ( i.e. , short-lived) perturbation factors (LPFs). These responses include behavioral and physiological changes that enhance survival and collectively make up the “emergency” life history stage. There is considerable evidence that glucocorticosteroids, and other hormones in the hypothalamo—pituitary—adrenal (HPA) cascade, initiate and orchestrate the emergency life history stage within minutes to hours. This stage has a number of sub—stages that promote survival and avoid potential deleterious effects of stress that may result from chronically elevated levels of circulating glucocorticosteroids over days and weeks. These sub—stages may include: redirection of behavior from a normal life history stage to increased foraging, irruptivetype migration during the day, enhanced restfulness at night, and elevated gluconeogenesis. Once the perturbation passes, glucocorticosteroids may also promote recovery. Additional evidence from birds indicates that glucocorticosteroid responses to a standardized capture, handling and restraint protocol are modulated both on seasonal and individual levels. Field work reveals that these changes in responsiveness to LPFs have ecological bases, such as reproductive state, body condition etc., that in turn indicate different hormonal control mechanisms in the HPA cascade.

1,269 citations


"Stress, reproduction, and adrenocor..." refers background in this paper

  • ...In the short term, corticosterone can trigger behavioral and physiological changes that could facilitate the animal’s survival (Wingfield et al., 1998; Wingfield and Ramenofsky, 1999)....

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  • ...This may maximize reproductive success although it may also increase mortality (Wingfield et al., 1998)....

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  • ...Physiological effects can include mobilizing energy stores, gluconeogenesis, and suppressing growth and reproduction (Greenberg and Wingfield, 1987; Wingfield et al., 1998)....

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  • ...This may maximize reproductive success although it may also increase mortality (Wingfield et al., 1998)....

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  • ...Behavioral effects can include suppressing reproductive and territorial behaviors and promoting escape behaviors (Wingfield et al., 1998)....

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Journal ArticleDOI
TL;DR: The results lend support to the use of corticosterone as a rapid quantitative predictor of survival in wild animal populations and predicted overall population health during the 1998 El Niño famine and the 1999 La Niña feast period.
Abstract: Plasma levels of corticosterone are often used as a measure of “stress” in wild animal populations. However, we lack conclusive evidence that different stress levels reflect different survival probabilities between populations. Galapagos marine iguanas offer an ideal test case because island populations are affected differently by recurring El Nino famine events, and population-level survival can be quantified by counting iguanas locally. We surveyed corticosterone levels in six populations during the 1998 El Nino famine and the 1999 La Nina feast period. Iguanas had higher baseline and handling stress-induced corticosterone concentrations during famine than feast conditions. Corticosterone levels differed between islands and predicted survival through an El Nino period. However, among individuals, baseline corticosterone was only elevated when body condition dropped below a critical threshold. Thus, the population-level corticosterone response was variable but nevertheless predicted overall population health. Our results lend support to the use of corticosterone as a rapid quantitative predictor of survival in wild animal populations.

488 citations


"Stress, reproduction, and adrenocor..." refers background in this paper

  • ...Basal levels of corticosterone in marine iguanas, garter snakes, and two species of agamid lizard (Amphibolurus nuchalis, Pagona barbatus) are also negatively correlated with body condition (Bradshaw, 1986; Cree et al., 2000; Moore et al., 2000b; 2001; Romero and Wikelski, 2001)....

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  • ...Romero and Wikelski (2001) hypothesized that for individuals in very poor body condition, the increased capacity to produce corticosterone could be a physiological trait that enhances survival....

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  • ...They endure chronic starvation and mass mortality due to El Niño events (Romero and Wikelski, 2001)....

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  • ...Basal levels of corticosterone in marine iguanas, garter snakes, and two species of agamid lizard (Amphibolurus nuchalis, Pagona barbatus) are also negatively cor- related with body condition (Bradshaw, 1986; Cree et al., 2000; Moore et al., 2000b; 2001; Romero and Wikelski, 2001)....

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  • ...Galápagos marine iguanas, in poor physical condition due to a severe El Niño event, increased both basal levels of corticosterone and the magnitude of their adrenocortical response to capture stress (Romero and Wikelski, 2001; Fig....

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Journal ArticleDOI
TL;DR: The promise of nonpeptide CRH type-1 receptor antagonists to directly target the stress system in the brain is highlighted and the implications of aberrant stress system activity on physical and mental health are outlined.

476 citations


"Stress, reproduction, and adrenocor..." refers background in this paper

  • ...Increasingly, the hypothalamo–pituitary–adrenocortical (HPA) axis is viewed as a complex physiological system that can mediate large variation in the physiological and behavioral responses of animals to stressors (Sapolsky, 1992)....

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